Thanks, but the join clause is there, it's just buried in the subqueries.
If there is a problem, it is probably that the loop never ends.
Or it could be that the answer is exponential, and I just have too many
rows in the source table and too deep a graph.
I figured out how to do it in the application with one call to the
database and a simple recursive method in a class, though, so I'm not
going to use a stored function in the DB.
Thanks again for responding.
Chas.
Tom Lane wrote:
"Charles F. Munat" <chas@xxxxxxxxx> writes:
Using pseudocode from Celko's "SQL for Smarties" book, I wrote the
following function that builds a path enumeration table. I hope to
trigger this function on the rare occasions that the organizations table
is updated. But when I run this function, it hangs.
I think there might be something wrong with this query:
INSERT INTO organizations_path_enum
SELECT o1.parent_id, r1.child_id, (o1.depth + 1)
FROM organizations_path_enum o1, relationships r1
-- advance existing paths by one level
WHERE EXISTS (SELECT * FROM organizations_path_enum AS o2
WHERE r1.parent_id = o2.child_id)
-- insert only new rows into the table
AND NOT EXISTS (SELECT * FROM organizations_path_enum AS o3
WHERE o1.parent_id = o3.parent_id AND r1.child_id = o3.child_id);
I'm not totally clear on what this is supposed to accomplish, but
it seems like there should be some join clause between o1 and r1.
regards, tom lane
